Field of the Invention
The invention relates to a device for adjusting, for example, engaging and disengaging or throwing off printing unit cylinders in rotary printing presses, especially for web-fed rotary printing presses.
The published European Patent Document EP 0 193 012 A2 relates to a rotary printing press with a device for adjusting printing unit cylinders between one position, in which bearer rings of the printing unit cylinders are disengaged or thrown off from one another, and another position in which the cylinders are positioned against or engaged with one another during a printing operation. The printing unit cylinders, in the disengaged or thrown-off position thereof, are subjected to force by springs which, in one embodiment described in this reference, exert a force on rotatably supported retaining or holding arms of the printing unit cylinders. In another embodiment of the invention defined in the aforementioned published European Patent Document EP 0 193 012 A2, the printing unit cylinders are supported on leaf spring-shaped elements which force the cylinders into the disengaged or thrown-off position thereof. A motor is provided that exerts a force directly on one of the cylinders in order to bring it out of the disengaged or thrown-off position thereof and place it in the engaged position thereof that is required for the printing operation. The other printing unit cylinders are moved out of the respective disengaged or thrown-off positions thereof and into the engaged position thereof during the printing mode, by forces which are transmitted via bearer or Schmitz rings connected to the printing unit cylinders.
The published European Patent Document EP 0 625 423 A1 discloses a printing unit having a skewing engagement and disengagement device. The printing unit includes a frame, a first and a second support bracket, and a lower and an upper plate cylinder. The first support bracket is movably mounted on the frame. One end of the upper plate cylinder is mounted so that it moves with the first support bracket. The second support bracket is also movably mounted on the frame. One end of the lower printing unit cylinder is supported so that it moves with the second support bracket. The printing unit also includes a skewing engagement and disengagement device. The engagement device moves the support brackets transversely to the frame, independently of one another. The engagement device swivels the support brackets with respect to the frame. The engagement device includes a control cylinder and a piston rod, which are provided between the two support brackets. The control cylinder and the piston rod are pivotally connected to the support bracket and are pivotable relative to this support bracket when the latter is adjusted transversely by the skewing engagement device. Via the disengagement or throw-off device, the support brackets can be skewed independently of one another, while nevertheless remaining connected to one another for the disengagement or throw-off operation.
In this embodiment, when the upper and the lower plate cylinder and the rubber blanket cylinder, respectively, are brought into engagement, the rubber blanket cylinders automatically engage with one another as well. This compulsory coupling of the rubber blanket cylinder engagement makes automating of the changing of printing forms considerably more difficult. The web of material remaining between the rubber blanket cylinders in the printing unit can tear when the printing forms are changed, which requires complicated re-threading of the web of material into the printing units, and consequently involves a considerable loss of time.
A remedy can indeed be provided by removing the lower rubber blanket and the lower rubber blanket sleeve, respectively, from the lower printing unit cylinder, so that the printing form on the upper plate cylinder can be replaced, and the reverse thereof, but this is a time-consuming way to maintain a gap within which the web of material can remain during the changing of printing forms in the printing unit.